You are correct. The XPAK is very effective in detecting Military Grade Explosives and also Homemade Explosives. We can teach users to effectively detect explosives in a couple hours and since the system has no warm up time or calibration requirement, it's ready when needed. Deploying large numbers of systems will help gather intelligence on individuals involved in bomb-making activities. We need to be offensive when dealing with this threat. Thanks for your comments.

Thanks for the kind comments. I always get a kick out of talking to engineers about the process – reminds me of my days on the other side of the table.

To your question about sensors, the unitactually makes use of an external biologicalsensor – the human eye. The paper has a coating that, when sprayed with the contrast-enhancing ink and irradiated in the UV, demonstrates color change in the presence of explosive materials. The user looks in the viewfinder -- if we see dark patches, they know there is something amiss.

As far as I am aware, there is no additional sensor. They could probably easily rig one up with a linear CMOS image sensor coupled with some sort of a graphics processor chip, but that would increase size, cost, and detection time. The focus for these guys was to develop a simple, robust, cost-effective unit that would provide near-real-time results at checkpoints, etc. It's a clever bit of minimalist engineering, I'd say.

Kristin, I think this hand held explosive detectors is very helpful to cops, who are serving in sensitive areas. We know that now a day's terrorism is a major headache for almost all governments/countries, where suspicious materials like TNT are using widely for Bomb blasts. I hope this machine can help the cops for an early detection of TNT presence.

This is a story in the old tradition of Design News -- where the writers would get into the heads of the engineers and reveal their thought processes as they stepped through the design. Nice job by the author. I am curious, though: What kind of sensor is used for an application like this?

I agree Ann and Beth, this is scary. So I'm all the more glad to see this product. Anything we can do to make attacks less likely and to make attacks less harmful is good news. Tools like this could have the effect of discouraging the use of explosives.

I agree, it's unfortunate that the design of this detector is necessary. But I'm sure glad to see it, and it will no doubt come in very handy. Getting the motors' weight down while still providing enough torque looks like it was quite a challenge. I like the addition of a sensor.

Scary that we have to think about ruggedizing and packaging a handheld explosives dectector so that it is sturdy enough to use on the job as opposed to in controlled, scientific environments. Scary state of the world, but I suppose a harsh reality. It was interesting to follow the logic of their various design choices as they took a technology and tried to make it more commercially viable.

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